DE 10 2005 004 933 B3 (corresponding to U.S. patent application Ser. No. 11/339,577 filed Jan. 26, 2006) discloses a device for measuring the body temperature of a living being with a sensor housing, which device has a first temperature sensor for detecting the skin temperature of the living being, on the one hand, and a second temperature sensor for detecting a second temperature, on the other hand, wherein the second temperature represents a temperature in the area of a side of the sensor housing facing away from the skin. The sensor housing comprises, furthermore, an analyzing unit, by means of which the body temperature of the living being is calculated according to a preset temperature formula by calculating the temperature difference between the temperatures measured by the first temperature sensor and the second temperature sensor and other parameters. In addition, the temperature formula according to the prior-art device has a compensation term, by means of which a heat flux due to energy losses which arises from the fact that the heat flux released by the body to the sensor housing of the device is not sent completely over the first temperature sensor to the second temperature sensor, is taken into account. The heat flux flowing off from the main heat flux laterally transversely between the first temperature sensor and the second temperature sensor is taken into account by the known compensation term. The prior-art device, which has proved, in principle, successful in practice, does, however, require a relatively long time until a correct body temperature value can be determined when it is used in a relatively cold environment, for example, at an ambient temperature of 5° C.